Monitoring device and method for soil stress and displacement around composite foundation pile of ram-compacted pile

Abstract

This invention provides a device and method for monitoring the stress and displacement of soil around a displacement pile composite foundation. The monitoring device includes a pressure monitoring unit, a displacement monitoring unit, a data processing unit, and a limiting device unit. The data transmission module of the data processing unit is mounted on the limiting device unit. The displacement monitoring unit includes a guide component and a displacement sensor. Several guide components are sequentially slidably nested, with one end of each guide component slidably nested within the limiting device unit. The displacement sensor is mounted on the limiting device unit and connected to the guide component via a displacement lead wire. The pressure monitoring unit includes a pressure sensor. Pressure sensors are mounted on each guide component. Both the pressure sensor and the displacement sensor are electrically connected to the data transmission module for transmitting displacement data and horizontal pressure data to the data transmission module. This invention achieves synchronous monitoring of pressure and displacement through the pressure sensor and displacement sensor, thereby dynamically capturing the continuous displacement and stress changes of the soil during the displacement process.

Description

Technical Field

[0001] This invention belongs to the field of pile perimeter soil monitoring technology, specifically relating to a monitoring device and method for monitoring the stress and displacement of the soil around a displacement pile composite foundation. Background Technology

[0002] Displacement piles (such as screw piles, static pressure piles, or hammer piles) are a type of pile that is forcibly driven into the foundation soil during the pile driving process. The pile compresses the surrounding soil, causing significant displacement and compaction, thereby increasing the bearing capacity of the foundation and reducing settlement. They are widely used in composite foundations. However, the strong "soil displacement effect" during pile driving is a double-edged sword. While reinforcing the foundation, it can also cause stress redistribution and significant displacement in the soil around the pile, potentially leading to engineering problems such as cracking or damage to nearby buildings and underground pipelines. Therefore, real-time and accurate monitoring of the stress and displacement of the soil around the pile during pile driving is crucial for optimizing construction parameters, assessing environmental impacts, verifying design theories, and ensuring project safety.

[0003] Currently, monitoring of soil stress and displacement around piles involves pre-embedding individual earth pressure cells or excavating wells, pits, and installing inclinometers. However, these methods have the following shortcomings:

[0004] 1. Limited measurement dimension: Earth pressure cells can only acquire local stress data at their installation points, while inclinometer measurements usually rely on manual, intermittent insertion of probes for data acquisition. This makes it impossible to capture dynamic and continuous data during pile driving. Therefore, the data obtained are isolated and discrete, which cannot comprehensively and accurately reflect the three-dimensional continuous distribution and dynamic evolution of stress and displacement in the soil around the pile during the pile driving process.

[0005] 2. Poor real-time performance: Because displacement piles are constructed using auger drilling or pile driving methods, machinery operates continuously during single-pile construction. To ensure personnel safety, data collection is conducted only after pile foundation construction is completed. This data collection method significantly lags behind the construction progress. Furthermore, the excavation of exploratory wells cannot provide real-time feedback simultaneously with the auger drilling or pile driving process. By the time monitoring data indicates a risk, construction has often progressed to a stage where adjustments are difficult, rendering the monitoring ineffective.

[0006] 3. Insufficient system integration: Stress monitoring and displacement monitoring are usually two independent systems. Stress monitoring generally uses earth pressure cells, while displacement monitoring generally uses inclinometers or surface displacement piles. It is difficult to collect stress and displacement monitoring data at the same depth and different ranges of the pile foundation, making it difficult to accurately correspond and integrate the monitoring data in time and space. This is not conducive to revealing the reinforcement mechanism of the foundation from a three-dimensional perspective. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide a monitoring device and method for monitoring the stress and displacement of the soil around the pile in a composite foundation of displacement piles. This device and method can stably acquire continuous monitoring data, thus solving the problem that traditional monitoring methods cannot acquire radial stress and horizontal displacement data of the soil around the pile in real time.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows.

[0009] A monitoring device for stress and displacement of soil around displacement pile composite foundations includes a pressure monitoring unit, a displacement monitoring unit, a data processing unit, and a limiting device unit. The data processing unit includes a data transmitting module and a data receiving module, with the data transmitting module mounted on the limiting device unit. The displacement monitoring unit includes a guide assembly and a displacement sensor for monitoring radial horizontal displacement data of the soil around the displacement pile. Several guide assemblies are sequentially slidably nested, with one end of the guide assembly furthest from the displacement pile slidably nested in the limiting device unit. Several displacement sensors are mounted on the limiting device unit and connected to one end of the corresponding guide assembly via displacement leads. The pressure monitoring unit includes a pressure sensor for monitoring radial horizontal pressure data of the soil around the displacement pile. Each guide assembly is equipped with a pressure sensor. Both the displacement sensor and the pressure sensor are electrically connected to the data transmitting module for transmitting the monitored horizontal displacement data and horizontal pressure data to the data transmitting module.

[0010] Furthermore, the guiding assembly includes a guide plate and a guide rod. One end of the guide rod is connected to the guide plate. The guide rod of the guiding assembly closer to the soil displacement pile passes through the guide plate of the adjacent end of the guiding assembly and is slidably nested in the guide rod of the adjacent end of the guiding assembly. The pressure sensor is provided at both ends of the guide plate. The guide rod of the guiding assembly away from the soil displacement pile is slidably nested in the limiting device unit. The other end of the guide rod of each guiding assembly is connected to the corresponding displacement lead wire.

[0011] Furthermore, the limiting device unit includes a limiting component and a transmission device compartment. The guide rod of the guiding component on the side away from the soil displacement pile slides and nests at one end of the limiting component. The other end of the limiting component is connected to one end of the transmission device compartment. A first wheel axle is provided inside the end of the transmission device compartment connected to the limiting component. The data transmission module and displacement sensor are provided at the other end of the transmission device compartment. The displacement lead passes through the transmission device compartment and the limiting component and surrounds the first wheel axle.

[0012] Furthermore, a second wheel axle is provided inside the end of the transmission equipment compartment that is connected to the limiting component. The pressure sensor is connected to the data transmission module through a pressure transmission line, which passes through the transmission equipment compartment and the limiting component and surrounds the second wheel axle.

[0013] Furthermore, pulleys are slidably sleeved on both the first and second wheel shafts, and the pressure transmission line and displacement lead line are respectively wound on the corresponding pulleys.

[0014] Furthermore, the limiting component includes a limiting cylinder and a limiting plate, with a pair of limiting plates arranged opposite each other on the radial sides of the limiting cylinder, and the guide rod of the guiding component on the side away from the displacement pile is slidably nested inside the limiting cylinder.

[0015] Furthermore, the displacement sensor is electrically connected to the data transmission module via a displacement transmission line.

[0016] Furthermore, the data transmission module includes a data transmission antenna and a battery. The displacement sensor and the pressure sensor are both electrically connected to the data transmission antenna. The battery is electrically connected to the data transmission antenna for power supply. The data receiving module includes a data acquisition instrument and a data receiving antenna. The data receiving antenna and the data transmission antenna are wirelessly connected.

[0017] Furthermore, the pressure sensor is an earth pressure cell, and the displacement sensor is a wire-type displacement sensor.

[0018] This invention also provides a method for monitoring the stress and displacement of the soil around a displacement pile composite foundation. The method, using the monitoring device for the stress and displacement of the soil around a displacement pile composite foundation according to this invention, includes the following steps:

[0019] Step S1: Mark out the center point and the area of ​​influence of the soil displacement pile at the test site;

[0020] Step S2: Arrange the excavation outline within the displacement influence range around the center point of the displacement pile.

[0021] Step S3: Excavate a pit according to the excavation outline and install a monitoring device in the pit;

[0022] Step S4: Backfill the pit;

[0023] Step S5: Construct the displacement piles and collect and monitor the radial horizontal displacement data and horizontal pressure data of the soil around the displacement piles.

[0024] The present invention, by adopting the above technical solution, has the following advantages and effects:

[0025] This invention provides a device and method for monitoring the stress and displacement of soil around a displacement pile composite foundation. Multiple guide components are arranged radially and nested around the outer periphery of the displacement pile. A pressure sensor is installed on each guide component, and a displacement sensor connected to the guide component is also installed. During the construction of the displacement pile, the guide components move under force, enabling synchronous monitoring of stress and displacement at different radial depths and foundation depths. This covers the three-dimensional space of the soil around the pile, forming a continuous and synchronous monitoring of stress and displacement, thereby dynamically capturing the continuous displacement and stress changes of the soil during the displacement process.

[0026] The present invention provides a device and method for monitoring the stress and displacement of soil around displacement piles in composite foundations. During the construction of displacement piles, the monitoring data can be continuously sent to the office site without waiting for the completion of construction for manual reading. It has strong real-time performance and can dynamically adjust the construction parameters in a timely manner based on the monitoring data. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the vertical cross-sectional structure of the monitoring device of the present invention.

[0028] Figure 2 This is a schematic diagram of the horizontal cross-sectional structure of the monitoring device of the present invention.

[0029] The attached diagram is labeled as follows: 1-Displacement pile, 11-Displacement influence range, 2-Pressure sensor, 21-Pressure transmission line, 3-Guide assembly, 31-Guide rod, 32-Guide plate, 33-Displacement lead wire, 34-Displacement sensor limiting beam, 35-Displacement sensor, 4-Limiting assembly, 41-Limiting plate, 42-Limiting cylinder, 5-First wheel axle, 51-Second wheel axle, 6-Data transmission module, 61-Data transmission antenna, 62-Battery, 7-Transmission equipment compartment, 8-Excavation outline. Detailed Implementation

[0030] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings to provide a clearer understanding of the purpose, features, and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative of the essential spirit of the technical solution of the present invention.

[0031] like Figure 1 , Figure 2As shown in the diagram, this invention provides a monitoring device for the stress and displacement of soil around a displacement pile composite foundation. The device includes a pressure monitoring unit, a displacement monitoring unit, a data processing unit, and a limiting device unit. One end of the displacement monitoring unit is connected to the limiting device unit. The displacement monitoring unit monitors the radial horizontal displacement data of the soil surrounding the displacement pile 1. The pressure monitoring unit is connected to the displacement monitoring unit and monitors the radial horizontal pressure data of the soil surrounding the displacement pile 1. The data processing unit includes a data transmitting module 6 and a data receiving module. The data transmitting module 6 is mounted on the limiting device unit and electrically connected to the pressure monitoring unit and the displacement monitoring unit. The data processing unit receives and processes the horizontal pressure and horizontal displacement data monitored by the pressure monitoring unit and the displacement monitoring unit. The limiting device unit is used to fix and protect the pressure monitoring unit, the displacement monitoring unit, and the data transmitting module. The data receiving module is installed in an office space for collecting and analyzing the horizontal pressure and horizontal displacement data.

[0032] Furthermore, the displacement monitoring unit includes a guide assembly 3 and a displacement sensor 35. The displacement sensor 35 is used to monitor the horizontal displacement data of the soil surrounding the displacement pile 1. Several guide assemblies 3 are sequentially slidably nested. The end of the guide assembly 3 closest to the front end of the displacement pile 1 faces the displacement pile 1, while the end of the guide assembly 3 furthest from the rear end of the displacement pile 1 is slidably nested into a limiting device unit. Several displacement sensors 35 are mounted on the limiting device unit and are respectively connected to one end of the corresponding guide assembly 3 via displacement leads 33. The pressure monitoring unit includes a pressure sensor 2, which is used to monitor the horizontal pressure data of the soil surrounding the displacement pile 1. Pressure sensors 2 are mounted on each guide assembly 3. Both the pressure sensor 2 and the displacement sensor 35 are electrically connected to the data transmission module 6 to transmit the monitored horizontal pressure data and horizontal displacement data to the data transmission module 6. The data receiving module is wirelessly connected to the data transmission module 6 to receive the horizontal pressure data and horizontal displacement data transmitted by the data transmission module 6.

[0033] Specifically, in this invention, the guide component 3 includes a first guide component, a second guide component, a third guide component, and a fourth guide component. The first guide component, the second guide component, the third guide component, and the fourth guide component are connected in a sliding nested manner. The front end of the first guide component is set towards the side of the displacement pile 1, and the rear end of the fourth guide component is slidably nested in one end of the limiting device unit. The data transmission module 6 is set at the other end of the limiting device unit, and the limiting device unit has an L-shaped box structure.

[0034] As a preferred option, displacement sensor 35 is a wire-type displacement sensor, and pressure sensor 2 is a soil pressure cell.

[0035] Furthermore, the guide assembly 3 includes a guide plate 32 and a guide rod 31. One end of the guide rod 31 is connected to the guide plate 32. The guide rod 31 of the front end of the guide assembly 3 near the side of the displacement pile 1 passes through the guide plate 32 of the guide assembly 3 at the adjacent end and slides nested in the guide rod 31 of the guide assembly 3 at the adjacent end. Pressure sensors 2 are provided at both ends of the guide rod 31 extending from each guide plate 32. The guide rod 31 of the rear end of the guide assembly 3 away from the side of the displacement pile 1 slides nested in the limiting device unit. The other end of the guide rod 31 of each guide assembly 3 is connected to a corresponding displacement lead 33.

[0036] Specifically, the guide plate 32 and guide rod 31 are vertically connected to form a T-shaped structure, with both ends of the guide plate 32 extending radially outwards from the guide rod 31. A pressure sensor 35 is attached to the side of the guide plate 32 furthest from the displacement pile. The guide rods 31 are all cylindrical, and the guide plates 32 are all plate-shaped, with both ends bent towards the displacement pile. The two bent ends are opposite to the central axis of the displacement pile 1. The pressure sensor 35 is positioned on the bent ends to ensure that it senses the radial compressive force of the displacement pile 1.

[0037] In this invention, the guide plate of the first guide component faces the side of the displacement pile, the guide rod of the first guide component passes through the guide plate of the second guide component and then slides and nests inside the guide rod of the second guide component, the guide rod of the second guide component passes through the guide plate of the third guide component and then slides and nests inside the guide rod of the third guide component, the guide rod of the third guide component passes through the guide plate of the fourth guide component and then slides and nests inside the guide rod of the fourth guide component, and the guide rod of the fourth guide component slides and nests into one end of the limiting device unit.

[0038] Furthermore, the limiting device unit includes a limiting component 4, a first wheel axle 5, and a transmission device compartment 7. The guide rod 31 of the guide component 3 at the rear end away from the soil displacement pile 1 slides and nests one end of the limiting component 4. The other end of the limiting component 4 is connected to one end of the transmission device compartment 7. The first wheel axle 5 is installed inside the end of the transmission device compartment 7 connected to the limiting component 4. The data transmission module 6 and displacement sensor 35 are installed at the other end of the transmission device compartment 7. The displacement lead 33 passes through the transmission device compartment 7 and the limiting component 4 and rotates around the first wheel axle 5.

[0039] Specifically, the limiting component 4 includes a limiting cylinder 42 and limiting plates 41. A pair of limiting plates 41 are arranged opposite each other on the radial sides of the limiting cylinder 42 to form a T-shaped structure. The axial direction of the limiting cylinder 42 is opposite to the radial direction of the displacement pile 1. The limiting plates 41 are perpendicular to the limiting cylinder 42 to stop the limiting component 4. In this invention, the guide rod of the fourth guide component at the rear end away from the displacement pile 1 is slidably nested in the limiting cylinder 42. The transmission equipment compartment 7 is a rectangular frame structure. The transmission equipment compartment 7 is vertically connected to one end of the limiting cylinder 42. A first wheel axle 5 is provided in the lower end of the transmission equipment compartment 7. The two ends of the first wheel axle 5 are nested on the compartment wall of the transmission equipment compartment 7. The radial direction of the first wheel axle 5 is opposite to the axial direction of the limiting cylinder 42. The displacement lead 33 passes through the limiting cylinder 42, turns around the first wheel axle 5, and then passes through the transmission equipment compartment 7 to connect with the displacement sensor 35. The upper end of the transmission equipment compartment 7 is also provided with a displacement sensor limiting beam 34 for fixing the displacement sensor 35.

[0040] Furthermore, the data transmission module 6 is electrically connected to the pressure sensor 2 and the displacement sensor 35 to receive horizontal pressure data and horizontal displacement data.

[0041] Specifically, pressure sensor 2 and data transmission module 6 transmit horizontal pressure data via a wired connection. A second wheel axle 51 is internally located at the end of the transmission equipment compartment 7 connected to the limiting component 4. Pressure sensor 2 is connected to data transmission module 6 via pressure transmission line 21, which passes through the transmission equipment compartment 7 and the limiting component 4 and rotates around the second wheel axle 51. Displacement sensor 35 and data transmission module 6 transmit horizontal displacement data via a wired connection, i.e., displacement sensor 35 and data transmission module 6 are electrically connected via a displacement transmission line.

[0042] As a preferred option, the pressure sensor 2 and the data transmission module 6 transmit horizontal pressure data wirelessly. In this case, the pressure transmission line 21 is not required, and the second wheel axle 51 is not installed in the transmission equipment compartment 7.

[0043] As a preferred option, the displacement sensor 35 and the data transmission module 6 use a wireless method to transmit horizontal displacement data, in which case no displacement transmission line is required.

[0044] Furthermore, when the pressure transmission line 21 is used, in order to prevent damage to the pressure transmission line 21 and the displacement lead 33, and at the same time reduce the resistance of the pressure transmission line 21 and the displacement lead 33, pulleys are slidably sleeved on both the first wheel shaft 5 and the second wheel shaft 51. The pressure transmission line 21 and the displacement lead 33 are respectively wound on the corresponding pulleys, thereby reducing the friction when the pressure transmission line 21 and the displacement lead 33 turn.

[0045] Furthermore, the data transmission module 6 includes a data transmission antenna 61 and a battery 62. The displacement sensor 35 is connected to the data transmission antenna 61 via a displacement transmission line or wirelessly. The pressure sensor 2 is connected to the data transmission antenna 61 via a pressure transmission line 21 or wirelessly. The battery 62 is electrically connected to the data transmission antenna 61 for power supply. The pressure sensor 2 and the displacement sensor 35 transmit horizontal pressure data and horizontal displacement data to the data transmission antenna 61, respectively. The data receiving module includes a data acquisition unit and a data receiving antenna. The data receiving antenna is electrically connected to the data acquisition unit and wirelessly connected to the data transmission antenna 61. The data transmission antenna 61 transmits the horizontal pressure data and horizontal displacement data to the data receiving antenna, which then transmits the horizontal pressure data and horizontal displacement data to the data acquisition unit for processing and use.

[0046] When using the monitoring device of the present invention, firstly, according to the size of the monitoring device, an excavation outline 8 is planned on the outer periphery of the displacement pile 1. Then, a pit is excavated according to the excavation outline 8, the monitoring device is placed in the pit, and monitoring is carried out after backfilling.

[0047] This invention also provides a method for monitoring the stress and displacement of the soil around displacement piles in composite foundations. Displacement piles are based on the cylindrical expansion theory, where concrete piles or drill rods of a certain diameter are driven into the foundation using hammer driving, static pressure piles, or spiral displacement piles to compact the soil around the pile, increasing its bearing capacity and forming a composite foundation composed of the pile and the surrounding soil. During the construction of displacement piles, the soil around the pile expands outwards, forming different stress and displacement fields centered on the pile. Therefore, based on the reinforcement principle of displacement piles, this invention arranges pressure sensors and displacement sensors at different radial ranges and depths around the pile to obtain the deformation characteristics of the stress and displacement of the soil around the pile at different radial ranges and depths.

[0048] This invention provides a method for monitoring the stress and displacement of soil around displacement pile composite foundations. The method utilizes the monitoring device for monitoring the stress and displacement of soil around displacement pile composite foundations as described in this invention, and includes the following steps:

[0049] Step S1: Mark out the center point of the soil displacement pile 1 and the soil displacement influence range 11 of the soil displacement pile 1 at the test site.

[0050] Specifically, according to the experimental design, the test site is first leveled, and then the center point of the displacement pile 1 and the displacement influence range 11 of the displacement pile 1 are marked out on the test site. In order to ensure the normal operation of the monitoring device, the displacement influence range of compaction piles, rammed cement-soil piles and screw piles can be used as a reference. In this invention, the displacement influence range 11 of the displacement pile is selected as three times the pile diameter when marking out on the test site.

[0051] Step S2: Based on the center point of the displacement pile 1 and the size of the displacement influence range 11, arrange the excavation outline 8 within the displacement influence range 11 around the center point. The excavation outline 8 is located within the displacement influence range 11 around the displacement pile 1. The arrangement of the excavation outline 8 is determined according to the number and size of the monitoring devices. When multiple monitoring devices are installed, the excavation outline 8 is arranged symmetrically along the center of the displacement pile 1.

[0052] Step S3: Excavate a pit according to the excavation outline 8, and install a monitoring device in the pit.

[0053] Specifically, since the displacement pile 1 causes surface uplift while laterally compacting the foundation, the uplifted area during the construction of the displacement pile is about 1m below the ground surface. Therefore, the excavation depth of the pit should be at least 1m below the ground surface.

[0054] When using multi-layer three-dimensional position monitoring, the monitoring devices should be arranged vertically in multiple layers. The uppermost monitoring device should be installed at least 1 meter below the ground surface, and the vertical spacing between adjacent monitoring devices should be greater than 1 meter. The pit can be excavated using a Luoyang shovel. After the pit is excavated, the sidewalls should be trimmed according to the excavation outline 8. After cleaning the loose soil at the bottom of the pit, it should be leveled with standard sand before installing the monitoring devices.

[0055] The installation process of the monitoring device of the present invention specifically includes the following steps:

[0056] Step S31: Connect the pressure sensor 2 and the pressure transmission line 21, and mark the serial numbers on the pressure sensor 2 and the pressure transmission line 21 to ensure that the pressure sensor 2 and the pressure transmission line 21 correspond one-to-one.

[0057] Step S32: Install the pressure sensor 2 on the guide plate 32 of the guide assembly 3, pass the pressure transmission line 21 through the guide rod 31 of the guide assembly 3 in sequence, connect the displacement lead 33 to the end of the guide rod 31 of each guide assembly 3, and then nest the guide rods 31 of the guide assembly 3 in sequence, and fit the guide rod 31 of the guide assembly 3 away from the rear end of the side away from the soil displacement pile 1 into the limiting cylinder 42 of the limiting assembly 4.

[0058] In step S33, the displacement sensor 35 is installed on the upper end of the transmission equipment compartment 7. The pressure transmission line 21 and the displacement lead 33 are passed through the limiting component 4 of the limiting device unit and the transmission equipment compartment 7. The pressure transmission line 21 and the displacement lead 33 are turned after passing around the pulley. Then, the transmission equipment compartment 7 is bolted to the limiting component 4. The pressure transmission line 21 is connected to the data transmission antenna 61, and the displacement lead 33 is connected to the displacement sensor 35. The displacement sensor 35 is then connected to the data transmission antenna 61 through the displacement transmission line. After installation, the pressure sensor 2 and the displacement sensor 35 are tested to ensure that the connection is normal.

[0059] Step S34: Use a leveling rod to ensure that the monitoring device is placed horizontally, thus completing the installation of the monitoring device.

[0060] Step S4: Backfill and compact standard sand in layers in the pit to cover the monitoring device, and then trim the surface.

[0061] Specifically, when backfilling and compacting the standard sand in the pit, manual backfilling is used, with each layer not exceeding 20cm in thickness. After the standard sand is filled to 20cm above the guide component 3, it is compacted manually. After backfilling and compacting the standard sand in the pit, the surface of the test site is leveled, the monitoring device is marked, and the center point of the displacement pile 1 is marked again.

[0062] Step S5: Based on the center point of the laid-out displacement pile 1, construct the displacement pile. During construction, simultaneously collect and monitor the radial horizontal pressure and horizontal displacement data of the soil surrounding the displacement pile 1. Pay attention to the markings on the monitoring device during construction and avoid disturbing it. For data acquisition, read the initial monitoring data before construction and then read the dynamic monitoring data during construction.

Claims

1. A monitoring device for the stress and displacement of soil around a displacement pile composite foundation, characterized in that, The system includes a pressure monitoring unit, a displacement monitoring unit, a data processing unit, and a limiting device unit. The data processing unit includes a data transmitting module (6) and a data receiving module, and the data transmitting module (6) is mounted on the limiting device unit. The displacement monitoring unit includes a guide component (3) and a displacement sensor (35) for monitoring the radial horizontal displacement data of the soil around the displacement pile (1). Several guide components (3) are sequentially nested, and one end of the guide component (3) on the side away from the displacement pile (1) is nested in the limiting device unit. Several displacement sensors (35) are mounted on the limiting device unit and are respectively connected to one end of the corresponding guide component (3) through a displacement lead (33). The pressure monitoring unit includes a pressure sensor (2) for monitoring the radial horizontal pressure data of the soil around the displacement pile (1). The pressure sensor (2) is mounted on each guide component (3). Sensor (2), the displacement sensor (35) and the pressure sensor (2) are both electrically connected to the data transmission module (6) to transmit the monitored horizontal displacement data and horizontal pressure data to the data transmission module (6); the guide assembly (3) includes a guide plate (32) and a guide rod (31). One end of the guide rod (31) is connected to the guide plate (32). The guide rod (31) of the guide assembly near the side of the displacement pile (1) passes through the guide plate (32) of the guide assembly at the adjacent end and slides nested in the guide rod (31) of the guide assembly at the adjacent end. The pressure sensor (2) is provided at both ends of the guide plate (32). The guide rod (31) of the guide assembly away from the side of the displacement pile (1) slides nested in the limiting device unit. The other end of the guide rod (31) of each guide assembly is connected to the corresponding displacement lead (33).

2. The monitoring device for soil stress and displacement around displacement piles in composite foundations according to claim 1, characterized in that, The limiting device unit includes a limiting component (4) and a transmission device compartment (7). The guide rod (31) of the guide component on the side away from the soil displacement pile (1) slides and nests at one end of the limiting component (4). The other end of the limiting component (4) is connected to one end of the transmission device compartment (7). The end of the transmission device compartment (7) connected to the limiting component (4) is provided with a first wheel axle (5). The other end of the transmission device compartment (7) is provided with the data transmission module (6) and the displacement sensor (35). The displacement lead (33) passes through the limiting component (4) and the transmission device compartment (7) and surrounds the first wheel axle (5).

3. The monitoring device for soil stress and displacement around displacement piles in composite foundations according to claim 2, characterized in that, The transmission equipment compartment (7) is connected to the limiting component (4) and a second wheel axle (51) is provided inside. The pressure sensor (2) is connected to the data transmission module (6) through a pressure transmission line (21). The pressure transmission line (21) passes through the limiting component (4) and the transmission equipment compartment (7) and surrounds the second wheel axle (51).

4. The monitoring device for soil stress and displacement around displacement piles in composite foundations according to claim 3, characterized in that, Both the first wheel axle (5) and the second wheel axle (51) are slidably fitted with pulleys, and the pressure transmission line (21) and the displacement lead line (33) are respectively wound on the corresponding pulleys.

5. The monitoring device for soil stress and displacement around displacement piles in composite foundations according to claim 3, characterized in that, The limiting component (4) includes a limiting cylinder (42) and a limiting plate (41). A pair of limiting plates (41) are arranged opposite each other on the radial sides of the limiting cylinder (42). The guide rod (31) of the guide component (3) on the side away from the soil displacement pile (1) is slidably nested in the limiting cylinder (42).

6. The monitoring device for soil stress and displacement around displacement piles in composite foundations according to claim 5, characterized in that, The displacement sensor (35) is connected to the data transmission module via a displacement transmission line.

7. The monitoring device for soil stress and displacement around displacement piles in composite foundations according to claim 5, characterized in that, The data transmission module (6) includes a data transmission antenna (61) and a battery (62). The displacement sensor (35) and the pressure sensor (2) are both electrically connected to the data transmission antenna (61). The battery (62) is electrically connected to the data transmission antenna (61) for power supply. The data receiving module includes a data acquisition instrument and a data receiving antenna. The data receiving antenna and the data transmission antenna (61) are wirelessly connected.

8. The monitoring device for soil stress and displacement around displacement piles in composite foundations according to claim 6, characterized in that, The pressure sensor (2) is an earth pressure cell, and the displacement sensor (35) is a wire-type displacement sensor.

9. A method for monitoring the stress and displacement of soil around displacement pile composite foundations, comprising using the monitoring device for monitoring the stress and displacement of soil around displacement pile composite foundations as described in any one of claims 1-8, characterized in that, The method includes the following steps: Step S1: Locate the center point of the soil displacement pile (1) and the soil displacement influence range (11) at the test site. Step S2, arrange the excavation outline (8) within the soil displacement influence range (11) around the center point of the soil displacement pile (1). Step S3: Excavate a pit according to the excavation outline (8) and install a monitoring device in the pit; Step S4: Backfill the pit; Step S5: Carry out the construction of the displacement piles and collect and monitor the radial horizontal displacement data and horizontal pressure data of the soil around the displacement piles (1).

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